Air circulating system for driers



April 21, 1942. A. o. HURXTHAL. 2,280,704

AIR CIRCULATING SYSTEM FOR DHIERS I Filed SDM. l2, 1939 2 Sheets-Sheet lApril 21, 1942.

A. O. HURXTHAL AIR GIRCULATING SYSTEM FOR DRIERS Filed Sept. l2, 1959 2Sheets-Sheet 2 Patented Apr. 2l, 1942 2,280,704 A1B CIRCULATING SYSTEMFOR DBIEBS Alpheus 0.

Proctor vpllia, Pa.,

Hurxthal. Wyncote; Pa.. Schwartz, Incorporated. Philadela corporation ofPennsylvania assignor to Application September 12, 1939, Serial No.294,526

1 Claim.

This invention relates to air circulating systems for driers. The objectof the present invention is to provide a special type oi' aircirculation in connection with a drier where `there must be norecirculation of the air over the heating coils but at the same timethere must be recirculation of the air through the material being dried.

In the present instance, the invention as disclosed as being applied tothat type of drier wherein the material undergoing treatment istransported through a suitable drying chamber containing conditionedlair in circulation, i. e. air of regulated temperature and/or humidity.

In the prior art driers of the above noted type, the drying air isnormally circulated Within the drying chamber, transversely thereof, ina manner to make repeated contacts with the material being advancedthrough the drying chamber, and through a circulating compartment at oneside of the drying chamber wherein the air passes and makes contact withsuitable temperature regulating and/or humidifying units in its courseof circulation, between its successive contacts with the material in thedrying chamber.

In some instances, contact of the circulating air with the conditioningunits after initial contact oi the air with the material being treatedis undesirable because of dust or gaseous matters given oil? by somematerials becoming entrained in the drying air. and because such gasesor solid matters should not be permitted to come into contact with theheating or other conditioning units in the drier. Itis the object of thepresent invention to provide an eiilcient apparatus of simple compactconstruction for creating and maintaining an improved type of aircirculation to satisfy the above noted requirements.

ln the accompanying drawings:

Fig. 1 is a diagrammatic plan view of a multisection drier Iembodyingthe novel features of the present invention;

Fig. 2 is a transverse sectional elevation taken on the line 2-2, Fig.l; and

Fig, 3 is an enlarged longitudinal sectional view of one of the aircirculating devices employed for producing and maintaining th'e improvedcirculation in accordance with the principles of the presmt invention.

As shown in Fig. 1, the apparatus includes a drying chamber A whichpreferably is composed of a plurality of sections A1, A, A3, A4, A5, forexample. Each lsection extends transversely of the drier as a wholebetween the side walls i and 2 thereof, the roof I, and a sub-floor 4which is spaced above and parallel to the bottom 5 of thedrier.

Adapted to travel longitudinally through the drying chamber A,successively through the adjacently disposed sections thereof, is aconveyer of a horizontal endless belt type, the carrying run 8 of whichis disposed in a plane intermediate the roof 2 and sub-flooring 4, whilethe return run 1 travels through the space 8 formed between the ooring 4and the bottom li. The various sections of the drying chamber A areseparated by transversely extending partitions i in which are formedopenings Il .for passage of the conveyer run 8.

At one side of and spaced laterally from each cr any predeterminednumber of the sections A1,

A2. etc. is an air conditioning chamber I2, in which is mounted asuitable heating and/or humidifying unit i3. Admission oi' air to theupper end of each conditioning chamber i2 is controlled by an adjustabledamper i4, whereby predetermined quantities of extraneous air may passinto the conditioning chamber from the outside atmosphere and throughthe conditioning unit I3 for initial regulation of temperature and/orhumidity for subsequent entrance into the drying chamber A.

In a compartment i5 disposed intermediate the drying chamber A and theair conditioning chamber l2, for each of the sections A1, A, etc.thereof respectively, is an air impeller i6. As shown in Fig. 3, eachimpeller i6 comprises a rotor I1 composed of a pair of axially spacedconcentric frusto-conical annular end plates i8,

Abetween which impeller blades i9, i9 extend in a general axialdirection.

Intermediate the opposite end plates i8, i8 of each rotor i'i, theimpeller i6 is provided with a transversely extending disc 20 whichdivides the impeller blades i9 into relatively short and long sectionsi9* and i8b respectively., The disc 20 is supported by a suitable hub 2|in which one end of a supporting and driving shaft for the rotor il issuitably secured.

'I'he shaft 22 oi' each rotor Il, as shown in Fig. 2, extends completelythrough the conditioning chamber i2 to and through the outside wall 9 ofthe conditioning chamber i2 to a driving motor 24 which is secured tothe wall 9, outside the drier. If desired, a bearing 25 may be providedfor the shaft 22 adjacent the inner wall 26 oiV the conditioning chamberI2.

Secured to the wail 26, and affording communication between theconditioning chamber As each impeller. I1 is rotated by its motor 24,

air is simultaneously drawn from the conditioning chamber l2, throughthe duct 21 by the blades I3, and from the lower portion 29 of thedrying chamber A, through the duct 23 by the blades I9, and is deliveredradially outward into a casing 30 which surrounds the rotor I1, withinthe intermediate compartment I5. The drawn air is conducted from thecasing 30 to an opening 32 in the upper portion of the'drying chamber Aby a duct 3l, in which the fresh extraneous air from the conditioningchamber I2 is' thoroughly mixed with the air simultaneously drawn fromthe drying chamber A the air passing through the inlet opening 32 beingsuitably deected, to pass downwardly in the drying chamber A, bysuitable louvers 33.

As indicated by the arrows in Fig. 2, the air initially enters thedrying chamber A, through the regulating damper I4 in the upper end ofthe conditioning chamber I2, under the impetus of the impeller I6, bywhich the air is drawn downwardly through the conditioning chamber I2and then moved upwardly into the upper portion f the drying chamber A,the air being: suitably conditioned enroute through the chamber I2before it enters the drying chamber A.

The air is also circulated transversely of the drying chamber A by therotor I1, by being drawn into the axial inlet 28 of the impeller I6 fromthe lower portion 29 of the drying chamber A, and driven outwardly fromthe peripheral discharge of the rotor I1 of the impeller into theimpeller casing 3|).l from which the air passes through the duct 3i andopening 32 into the upper portion of the drying chamber A, solely.

The drying air, afterits initial conditioning in the chamber I2, andafter its initial contact with the material supported by the conveyerrun 6, never again makes contact with the conditioning unit I3.

As freshly conditioned air is continuously supplied through theregulating damper I4, and' mixed, in the casing 30 and duct 3| with theair in circulation within the drier, a suitable quantity of moist air isexhausted from said circulation, through an exhaust duct 34communicating with the lower portion 29 of the drying chamber A, underthe impetus of a suitable exhaust ian 35 which is driven by anindependent motor 36, or equivalent means. If desired, there may be anexhaust fan 35 for each of the various sections of the drying chamber.However, under normal conditions, a single fan 35 may be operatedeiiciently to exhaust a suii'icient quantity of moist air from thedrying chamber A as a Whole.

As shown in Fig. l, the'sections Al and A2 are provided with individualdampers I4 and i4 respectively. The sections A39 A, and A5, however, aresupplied with fresh extraneous air from a single damper I4c whichcommunicates with a l single elongated conditioning chamber I2ELcomdevices of any of the types commonly known to the art, such, forexample, as wet and dry bulbs,

whereby the units I3 may be automatically controlled as well as thedampers I4. I4", and l4 which regulate the quantities of air admitted tothe respective conditioning chambers.

In some instances, it may be desirable to pass the air in circulationfrom one section to another, with or without adding fresh extraneous airthereto, in which case the dampers I4", I4b and I4 may be selectivelyclosed or opened and each or any desired number of the partitions I0,between the various sections, may be provided with an adjustable gate 31which is hingedly mounted at one oi' its ends to the partition I0 in anopening 33 formedin said partition, said gate 31 normally lying in theplane of the partition I0 and being adapted to be swung to either sidethereof at an angle thereto, as shown in broken lines in Fig. l, forcontrolling the passage of air from one section to the next, through anopening 38 formed in the partition I0 between the carrying run 6 of theconveyer and the sub-ilooring 4 of the drier.

From the above it will be clear that in a device constructed andoperatedas described, each secticn of the drier may have its ownindependent properly proportioned heating unit andl control, by whichsimilar or differential temperatures best suited to the speciilc dryingproblem at hand may be obtained and maintained throughout the length ofthe drier. Likewise the dampers for the extraneous air admitted to theconditioningv of the drier by any suitable means such as a ianofsuitable capacity having a construction similar to the exhaust fan 35,or an equivalent structure. Under such conditions, obviously, thesection of the drying chamber nearest the discharge end for the materialwould be of the highest temperature and of the lowest moisture content.

I claim:

A drier comprising a drying chamber devoid of any air conditioningmeans, means for circulating air solely within said drying chamber in acourse transversely thereof, a second chamber provided with airconditioning means, means for moving unconditioned air from outside saiddrier into said second chamber for initial conditioning and for movingthe initially conditioned air from said second chamber into thecirculation of air in said drying chamber, an air-intercepting gate insaid drying chamber for selectively diverting the'air circulating solelytherein and transversely thereof in either direction longitudinally ofsaid chamber from one portion of said transverse course of circulationin'to an adjacent portion of said transverse course of circulationsolely within said drying chamber, and means for discharging saidcirculating air to waste outside said drier.

V ALPHEus o. HURx'rHAL.

